1.0.0[−][src]Struct alloc_wg::fmt::Arguments
This structure represents a safely precompiled version of a format string and its arguments. This cannot be generated at runtime because it cannot safely be done, so no constructors are given and the fields are private to prevent modification.
The format_args!
macro will safely create an instance of this structure.
The macro validates the format string at compile-time so usage of the
write()
and format()
functions can be safely performed.
You can use the Arguments<'a>
that format_args!
returns in Debug
and Display
contexts as seen below. The example also shows that Debug
and Display
format to the same thing: the interpolated format string
in format_args!
.
let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2)); let display = format!("{}", format_args!("{} foo {:?}", 1, 2)); assert_eq!("1 foo 2", display); assert_eq!(display, debug);
Implementations
impl<'a> Arguments<'a>
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pub fn as_str(&self) -> Option<&'static str>
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fmt_as_str
)Get the formatted string, if it has no arguments to be formatted.
This can be used to avoid allocations in the most trivial case.
Examples
#![feature(fmt_as_str)] use core::fmt::Arguments; fn write_str(_: &str) { /* ... */ } fn write_fmt(args: &Arguments) { if let Some(s) = args.as_str() { write_str(s) } else { write_str(&args.to_string()); } }
#![feature(fmt_as_str)] assert_eq!(format_args!("hello").as_str(), Some("hello")); assert_eq!(format_args!("").as_str(), Some("")); assert_eq!(format_args!("{}", 1).as_str(), None);
Trait Implementations
impl<'a> Clone for Arguments<'a>
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impl<'a> Copy for Arguments<'a>
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impl<'_> Debug for Arguments<'_>
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impl<'_> Display for Arguments<'_>
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Auto Trait Implementations
impl<'a> !RefUnwindSafe for Arguments<'a>
impl<'a> !Send for Arguments<'a>
impl<'a> !Sync for Arguments<'a>
impl<'a> Unpin for Arguments<'a>
impl<'a> !UnwindSafe for Arguments<'a>
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T> ToString for T where
T: Display + ?Sized,
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T: Display + ?Sized,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,